Last week I sold my 97 2500 4x4 Suburban with a 7.4, it was hard watching her leave the driveway knowing she wouldnt be back.
Like someone else posted I'd hold off doing mods for now untill you get a feel for this truck. Spend some money cleaning, tuning, and fixing the little problems the last owner might not have repaired.
Not sure what type vehicle you previously owned but the fuel consumption of a 454 Suburban takes a little getting used to, before lifting and putting on bigger tires make sure you can live with the fuel consumption your presently getting.
Once the newness wears off mileage almost always becomes an issue, I know it did with mine which was why she sat in the driveway most days, this ultimately ended in selling her because she was driving less than 500 miles a year.